[chsarp] Add YogaKit Shared and iOS version

[rmarinho]

Using shared code for reuse in other platforms based on iOS native implementation.

Adds YogaKit sample.

Adds YogaKit tests (same as objc). (3 tests failing)

YogaKitTest : 80 ms
Facebook.YogaKit.iOS.Tests.exe : 81 ms
Tests run: 11 Passed: 8 Inconclusive: 0 Failed: 3 Ignored: 1

Since we don't have extension properties we need to go with a extension method to get access to the YogaLayout .

I m also not sure this is leak free yet, would love some help with testing and feedback about view/node lifecycle

[emilsjolander]

I'm worried about this copying a lot of logic from YogaKit. Can Xamarin interop with the obj-c code in YogaKit instead?

[rmarinho]

This is so we can share YogaKit implementation to other platforms like android and uwp.

I could do binding for the the YogaKit lib ... but that will only work for iOS.

[emilsjolander]

Aren't you tying yourself to iOS by doing [DllImport("/usr/lib/libobjc.dylib")] though?

[rmarinho]

That file only lives in the YogaKit iOS project, it's a partial class , so the methods are only added when you are running in that platform.

[emilsjolander]

Ok, makes sense. Thanks for taking the time to explain 👍 I'll let @splhack give the final ok on the c# code but it looks good to me.

[splhack]

I feel maybe we can have another approach for this. For example, this line from test.

root.Yoga().AlignItems = YogaAlign.Center;

It would be like next line if we can use YogaNode class directly.

root.Yoga.AlignItems = YogaAlign.Center;

I'll try to hack around YogaKit based on this PR later.

[rmarinho]

@splhack yeah maybe C# 7 or 8 will give us Extension Properties .

But i agree with you and open to a solution :)

[rmarinho]

Added tests

[facebook-github-bot]

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